Table of Contents
ISRN High Energy Physics
Volume 2013, Article ID 374612, 21 pages
http://dx.doi.org/10.1155/2013/374612
Research Article

From Generalized Dirac Equations to a Candidate for Dark Energy

Department of Physics, Missouri University of Science and Technology, Rolla, MO 65409, USA

Received 12 November 2012; Accepted 1 December 2012

Academic Editors: G. A. Alves, C. A. D. S. Pires, and F.-H. Liu

Copyright © 2013 U. D. Jentschura and B. J. Wundt. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We consider extensions of the Dirac equation with mass terms and . The corresponding Hamiltonians are Hermitian and pseudo-Hermitian ( Hermitian), respectively. The fundamental spinor solutions for all generalized Dirac equations are found in the helicity basis and brought into concise analytic form. We postulate that the time-ordered product of field operators should yield the Feynman propagator ( prescription), and we also postulate that the tardyonic as well as tachyonic Dirac equations should have a smooth massless limit. These postulates lead to sum rules that connect the form of the fundamental field anticommutators with the tensor sums of the fundamental plane-wave eigenspinors and the projectors over positive-energy and negative-energy states. In the massless case, the sum rules are fulfilled by two egregiously simple, distinguished functional forms. The first sum rule remains valid in the case of a tardyonic theory and leads to the canonical massive Dirac field. The second sum rule is valid for a tachyonic mass term and leads to a natural suppression of the right-handed helicity states for tachyonic particles and left-handed helicity states for tachyonic spin-1/2 antiparticles. When applied to neutrinos, the theory contains a free tachyonic mass parameter. Tachyons are known to be repulsed by gravity. We discuss a possible role of a tachyonic neutrino as a contribution to the accelerated expansion of the Universe “dark energy.”